Biomedical subjects

Xiangxu Chen

Publications and source records attributed to Xiangxu Chen.

4 recordsLinked to original sources

PubMed2005

[Terpenoids in root exudates of different allelopathic rice varieties].

In this paper, a strong allelopathic rice variety PI312777 and a weak allelopathic rice variety Lemont were used as test materials, and the root exudates of two rice varieties grown in the media of sand and soil were respectively collected by using circulation system approach. The terpenoids in ether-extracts were detected by GC-MS, and characterized by spectrum database. The results showed that some terpenoids such as limonene oxide, limonene dioxide, carvone oxide, carveol, and cedrol were detected in the ether-extracts. Different rice varieties had the similar kinds of terpenoids, but their existing modes and quantities were different. The differences between different various cultural methods and between rice varieties were further discussed.

Oryza↗

PubMed2005

[Allelopathy and resources competition of rice under different nitrogen supplies].

In order to explore the bio-interference of allelopathic rice with barnyardgrass under different nitrogen supplies, a new bioassay method, i.e., allelopathy-competition separation based (ACS) approach was recommended in this study. The results indicated that ACS could be successfully used to distinguish the rice allelopathy from its resources competition in rice-weed co-culture system, and to evaluate its response characteristics under different N supplies. The test rice accession PI312777 had a higher ability in interfering target weed barnyardgrass (BYD), represented by its stable and higher ability in resources competition, as well as its increasing allelopathic potential in suppressing companion weed BYD when the N supply decreased in the co-cultured system. The reverse was true in the case of rice accession Lemont, which had a lower allelopathic potential under all N supply levels, and a lower ability in resources competition under normal or rich N supply. But, Lemont had an obviously increased ability in resources competition under lower N supply, which was considered as the result of econiche competition in rice-weed system.

Echinochloa↗

PubMed2005

[Chemical components of root exudates from allelopathic rice accession PI312777 seedlings].

In this study, allelopathic rice accession PI312777 seedlings were grown on a paddy soil under near natural condition, and their root exudates were collected by using circulation method, with the solution collected from no seedlings- planted soil as the control. The ether extracts of the root exudates and soil solution were detected by GC-MS, and identified with the mass spectral database of NIST and WILEY Library. The results showed that there were 36 compounds in the rice root exudates, including 9 terpenoids (peak area 10.97%), 8 phenols or quinones (5.87%), 6 esters (10.68%), 3 aldehydes or ketones (1.44%), 4 heterocycles (68.04%), 2 alcohols (1.23%), 2 ethers (0.57%), and 2 others (1.20%). A distinctly similar structure was observed among the terpenoids and among the phenols or quinones. In the soil solution, 39 compounds were detected, and 7 of them were the same of the root exudates. The difference of the compounds in rice root exudates and soil solution, and the possible allelopathic mechanisms of these compounds were discussed in this paper.

Heterocyclic Compounds↗

PubMed2002

A thermally re-mendable cross-linked polymeric material.

We have developed a transparent organic polymeric material that can repeatedly mend or "re-mend" itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120 degrees C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of "intermonomer" linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.

Journal Article↗